1. Field of the Invention
This invention relates to a method of extracting DNA-containing cells from hair roots.
2. Discussion of the Prior Art
Currently, so-called FTA (trademark) cards are used to collect and preserve samples of body fluid for subsequent DNA analysis. The cards, which are available from Fitzco, Inc., are described in detail in U.S. Pat. No. 5,496,562, which issued to L. A. Burgoyne on Mar. 5, 1996. Basically, the cards are defined by a cellulose based, solid matrix absorbent paper impregnated with a composition consisting of a surfactant (sodium dodecyl sulfate), a chelate (ethylenediame tetraacetic acid), a weak base tris(hydroxymethyl) aminomethane and optionally uric acid or a urate salt.
Blood DNA stored on FTA cards can be amplified in situ using polymerase chain reaction (PCR). FTA cards constitute a quick, safe and efficient method of purifying DNA for use in PCR without the need for quantitation. FTA cards were originally intended for use with blood only, but have been shown to be equally effective for saliva or buccal samples.
A third common source of DNA in forensics is hair roots. However, the liberation of hair root DNA into a liquid medium for spotting on FTA cards proved to be difficult and time consuming. The available methods (organic, Chelex and Qiagen.RTM.) all start by taking hair roots and using them directly to produce either double or single stranded DNA. Organic methods use organic solvents and DNA precipitation to isolate usable DNA. The methods require personal protection gear to protect the operators and quantitation of the DNA before use. Chelex methods render the DNA in a single strand format suitable for PCR, but are not always reliable. The Qiagen methods require expensive materials, are not amenable to automation and are expensive.